Tumor suppressor candidate TUSC3 expression during rat testis maturation

Assessing genomic diversity and selective pressures in Bashan cattle by whole-genome sequencing data

Specific ecological environments and domestication have continuously influenced the physiological characteristics of Chinese indigenous cattle. Among them, Bashan cattle belongs to one of the indigenous breeds. However, the genomic diversity of Bashan cattle is still unknown. Published whole-genome sequencing (WGS) data of 13 Bashan cattle and 48 worldwide cattle were used to investigate the genetic composition and selection characteristics of Bashan cattle. The population structure analysis revealed that Bashan cattle harbored ancestries with East Asian taurine and Chinese indicine. Genetic diversity analysis implied the relatively high genomic diversity in Bashan cattle. Through the identification of containing >5 nsSNPs or frameshift mutations genes in Bashan cattle, a large number of pathways related to sensory perception were discovered. CLR, θπ ratio, FST, and XP-EHH methods were used to detect the candidate signatures of positive selection in Bashan cattle. Among the identified genes, most of the enriched signal pathways were related to environmental information processing, biological systems, and metabolism. We mainly reported genes related to the nervous system (HCN1, KATNA1, FSTL1, GRIK2, and CPLX2), immune (CD244, SLAMF1, LY9, and CD48), and reproduction (AKR1C1, AKR1C3, AKR1C4, and TUSC3). Our findings will be significant in understanding the molecular basis underlying phenotypic variation of breed-related traits and improving productivity in Bashan cattle.

SOX2 participates in spermatogenesis of Zhikong scallop Chlamys farreri

As an important transcription factor, SOX2 involves in embryogenesis, maintenance of stem cells and proliferation of primordial germ cell (PGC). However, little was known about its function in mature gonads. Herein, we investigated the SOX2 gene profiles in testis of scallop, Chlamys farreri. The level of C. farreri SOX2 (Cf-SOX2) mRNA increased gradually along with gonadal development and reached the peak at mature stage, and was located in all germ cells, including spermatogonia, spermatocytes, spermatids and spermatozoa. Knockdown of Cf-SOX2 using RNAi leaded to a mass of germ cells lost, and only a few spermatogonia retained in the nearly empty testicular acini after 21 days. TUNEL assay showed that apoptosis occurred in spermatocytes. Furthermore, transcriptome profiles of the testes were compared between Cf-SOX2 knockdown and normal scallops, 131,340 unigenes were obtained and 2,067 differential expression genes (DEGs) were identified. GO and KEGG analysis showed that most DEGs were related to cell apoptosis (casp2, casp3, casp8), cell proliferation (samd9, crebzf, iqsec1) and spermatogenesis (htt, tusc3, zmynd10, nipbl, mfge8), and enriched in p53, TNF and apoptosis pathways. Our study revealed Cf-SOX2 is essential in spermatogenesis and testis development of C. farreri and provided important clues for better understanding of SOX2 regulatory mechanisms in bivalve testis.

TUSC3 accelerates cancer growth and induces epithelial-mesenchymal transition by upregulating claudin-1 in non-small-cell lung cancer cells

Lung cancer is the most frequent cause of cancer-related deaths worldwide, but its molecular pathogenesis is poorly understood. The tumor suppressor candidate 3 (TUSC3) gene is located on chromosome 8p22 and is universally acknowledged as a cancer suppressor. However, our research has demonstrated that TUSC3 expression is significantly upregulated in non-small-cell lung cancer compared to benign controls. In this study, we analyzed the consequences of TUSC3 knockdown or overexpression on the biological functions of non-small-cell lung cancer cell lines. To identify the molecules and signaling pathways with which TUSC3 might interact, we completed immunoblotting, quantitative polymerase chain reaction, microarray, co-immunoprecipitation, and immunofluorescence assays. We demonstrated that TUSC3 knockdown leads to decreased proliferation, migration, and invasion, and reduced xenograft tumor growth of non-small-cell lung cancer cell lines, whereas opposite results were observed with overexpression of TUSC3. In addition, TUSC3 knockdown suppressed epithelial-mesenchymal transition by downregulating the expression of claudin-1, which plays an indispensable role in EMT progress. On the contrary, overexpression of TUSC3 significantly enhanced EMT progress by upregulating claudin-1 expression. Overall, our observations suggest that TUSC3 accelerates cancer growth and induces the epithelial-mesenchymal transition in non-small-cell lung cancer cells; we also identified claudin-1 as a target of TUSC3.

TUSC3: functional duality of a cancer gene

Two decades ago, following a systematic screening of LOH regions on chromosome 8p22, TUSC3 has been identified as a candidate tumor suppressor gene in ovarian, prostate and pancreatic cancers. Since then, a growing body of evidence documented its clinical importance in various other types of cancers, and first initial insights into its molecular function and phenotypic effects have been gained, though the precise role of TUSC3 in different cancers remains unclear. As a part of the oligosaccharyltransferase complex, TUSC3 localizes to the endoplasmic reticulum and functions in final steps of N-glycosylation of proteins, while its loss evokes the unfolded protein response. We are still trying to figure out how this mechanistic function is reconcilable with its varied effects on cancer promotion. In this review, we focus on cancer-related effects of TUSC3 and envisage a possible role of TUSC3 beyond endoplasmic reticulum.

TUSC3 induces autophagy in human non-small cell lung cancer cells through Wnt/β-catenin signaling

We investigated the effects of tumor suppressor candidate 3 (TUSC3) on autophagy in human non-small cell lung cancer (NSCLC) cells. A total of 118 NSCLC patients (88 males and 30 females) who underwent surgery at our institute were enrolled in the study. Immunohistochemical analysis revealed that TUSC3 protein expression was lower in NSCLC specimens than adjacent normal tissue. Correspondingly, there was greater methylation of TUSC3 in NSCLC than adjacent normal tissue. After transient transfection of A549 NSCLC cells with constructs designed to up-regulate or down-regulate TUSC3 expression, we analyzed the effects of inhibiting the Wnt pathway (XAV939) and autophagy (chloroquine, CQ) on the behavior of NSCLC cells. We also performed TOP/FOP-Flash reporter assays, MTT assays, Annexin V-FITC/propidium iodide staining, and acridine orange staining to evaluate Wnt/β-catenin signaling, cell proliferation, apoptosis, and autophagy, respectively. Expression of Wnt/β-catenin pathway components and autophagy-related proteins was analyzed using qRT-PCR and Western blotting. We found that TUSC3 inhibited cell proliferation and promoted both apoptosis and autophagy in A549 cells. In addition, TUSC3 increased expression of autophagy-related proteins. It also increased expression of Wnt/β-catenin signaling pathway components and promoted nuclear transfer of β-catenin, resulting in activation of Wnt/β-catenin signaling. TUSC3 thus induces autophagy in human NSCLC cells through activation of the Wnt/β-catenin signaling pathway.

Oncogenic function of TUSC3 in non-small cell lung cancer is associated with Hedgehog signalling pathway

Non-small cell lung cancer (NSCLC) represents 75-80% of all lung carcinomas, which is the most common cause of death from cancer. Tumour suppressor candidate 3 (TUSC3) is pivotal in many biochemical functions and cytological processes. Dis-regulation of TUSC3 is frequently observed in epithelial cancers. In this study, we observed up-regulated TUSC3 expression at the mRNA and protein levels in clinical NSCLC samples compared with adjacent non-tumorous lung tissues. The expression level of TUSC3 is significantly correlated with tumour metastasis and patient survival. Overexpression of TUSC3 in NSCLC cells led to increased proliferation, migration, and invasion in vitro and accelerated xenograft tumour growth in vivo, while the opposite effects were achieved in TUSC3-silenced cells. Increased GLI1, SMO, PTCH1, and PTCH2 abundance were observed in TUSC3 overexpressed cells using western blotting. Co-immunoprecipitation and immunofluorescence analyses further revealed interaction between TUSC3 and GLI1. In conclusion, our study demonstrated an oncogenic role of TUSC3 in NSCLC and showed that dis-regulation of TUSC3 may affect tumour cell invasion and migration through possible involvement in the Hedgehog (Hh) signalling pathway.

TUSC3: a novel tumour suppressor gene and its functional implications

The tumour suppressor candidate 3 (TUSC3) gene is located on chromosome region 8p22 and encodes the 34 kD TUSC3 protein, which is a subunit of the oligosaccharyl transferase responsible for the N‐glycosylation of nascent proteins. Known to be related to autosomal recessive mental retardation for several years, TUSC3 has only recently been identified as a potential tumour suppressor gene. Based on the structure and function of TUSC3, specific mechanisms in various diseases have been investigated. Several studies have demonstrated that TUSC3 is an Mg²⁺‐transporter involved in magnesium transport and homeostasis, which is important for learning and memory, embryonic development and testis maturation. Moreover, dysfunction or deletion of TUSC3 exerts its oncological effects as a modulator by inhibiting glycosylation efficiency and consequently inducing endoplasmic reticulum stress and malignant cell transformation. In this study, we summarize the advances in the studies of TUSC3 and comment on the potential roles of TUSC3 in diagnosis and treatment of TUSC3‐related diseases, especially cancer.

Effects of RNAi-mediated TUSC3 silencing on radiation-induced autophagy and radiation sensitivity of human lung adenocarcinoma cell line A549 under hypoxic condition

This study examined the effects of RNAi-mediated TUSC3 silencing on radiation-induced autophagy and radiation sensitivity of human lung adenocarcinoma cell line A549 under hypoxic condition. Different CoCl2 concentrations were used to treat A549 cells and establish a CoCl2-induced hypoxic model of A549 cells. MTT and clone formation assays were used to determine the effects of different concentrations of CoCl2 on the growth and proliferation of A549 cells treated by different doses of X-ray irradiation. The siRNA-expressing vector was transfected by liposomes and for silencing of TUSC3. Flow cytometry was used to measure cell cycle changes and apoptosis rate. Real-time quantitative polymerase chain reaction (qRT-PCR) assay was performed to detect the expression of TUSC3 mRNA. Western blotting was applied to detect the changes of TUSC3, LC3, and p62 proteins under different CoCl2 concentrations and after siRNA silencing of TUSC3. The TUSC3 levels in A549 cells increased under hypoxic conditions in a dose-dependent manner (P < 0.05). Hypoxia inhibited the growth and proliferation of A549 cells and promoted apoptosis (P < 0.05). With an increasing dose of X-ray irradiation, A549 cells showed significantly increased growth and proliferation and decreased apoptosis (P < 0.05). After siRNA-TUSC3 was transfected by liposome, the TUSC3 level was substantially inhibited (P < 0.05). Silencing TUSC3 inhibited A549 cell growth and proliferation after radiotherapy under hypoxic condition, promoted apoptosis, increased G0/G1 phase cells, and reduced S phase cells (all P < 0.05). Hypoxia and radiation along with different CoCl2 concentrations could induce cell autophagy, which increased with concentration and dose, while silencing the TUSC3 gene inhibited autophagy (all P < 0.05). RNAi silencing of TUSC3 inhibited growth and proliferation, while enhanced apoptosis and radiation sensitivity of hypoxic A549 lung adenocarcinoma cells.

Decreased Tumor Suppressor Candidate 3 Predicts Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma

TUSC3 was recently identified as a potential tumor suppressor gene in a variety of human malignancies. However, no data are currently available regarding the expressions of TUSC3 in esophageal cancer (ESCC).The purposes of this study was to investigated the expressions of TUSC3 in ESCC tissues and assess the relationship between TUSC3 levels and clinico-pathological characteristics of ESCC patients. TUSC3 protein expressions were evaluated by immunohistochemistry (IHC) on tissue microarray slides in esophageal cancer, which included 95 esophageal squamous carcinoma specimens (ESCC), and 75 normal esophageal mucosa (NEM). We found that TUSC3 in ESCC was significant lower than that in NEM (P=0.000). According to multi-clinical classifications, TUSC3 level varied significantly with TNM stage, T stage, and N stage (p<0.001, p=0.0368, p<0.0001, respectively). Univariate analysis showed that gender, TNM stage, T stage, N stage, TUSC3 expression were prognostic factors for survival. Multivariate analysis showed that in our study, only TUSC3 expression was independent prognostic factors for ESCC. Our results indicated for the first time, a combined analysis of TUSC3 expressions as well as the clinical variables will help predict the prognosis of ESCC patients. Further large-sample validation and functional analysis should be performed to evaluate its potential prognostic and therapeutic values for ESCC patients.

Tumor suppressor candidate 3 as a novel predictor for lymph node metastasis in lung cancer patients

Tumor suppressor candidate 3 (TUSC3) was recently identified as a potential tumor suppressor gene in several cancer types. However, no data are currently available regarding the expression of TUSC3 in lung cancer. The present study investigated the expression of TUSC3 in patients with lung cancer and determined its association with the clinicopathological parameters of the disease. Cytoplasmic TUSC3 expression was evaluated by immunohistochemistry on tissue microarray slides, which included 35 small cell lung cancer (SCLC) specimens, 80 squamous cell lung cancer specimens (SCC), 80 adenocarcinoma lung cancer (ADC) specimens and 37 normal lung tissue specimens. Analysis showed significantly reduced TUSC3 expression in the SCLC patients, but not in the ADC and SCC patients, as compared with the normal controls. Additionally, TUSC3 expression in the patients with a degree of differentiation of 1–2 (well-moderately differentiated) was significantly higher than that in patients with a differentiation degree of 3–4 (poorly differentiated-undifferentiated). Further analysis showed that TUSC3 expression levels were negatively correlated with the degree of differentiation in the ADC and SCC patients. Notably, a marked decrease in TUSC3 expression was identified in the patients who were lymph node metastasis-positive (LNM⁺) compared with patients who were LNM⁻. Further analysis showed that significant differences in TUSC3 expression were identified among the different N stages (LNM status) in the SCLC, ADC and SCC patients. Correlation analysis also identified a negative correlation between TUSC3 expression and LNM in all three pathological types of lung cancer tested. Overall, these results indicated that a reduction in TUSC3 may be associated with a poorly-differentiated grade of lung cancer. Importantly, TUSC3 expression may be a useful predictor of LNM in lung cancer patients. A combined analysis of TUSC3 expression and the clinical variables will aid in predicting the incidence of LNM.

TUSC3 promotes colorectal cancer progression and epithelial-mesenchymal transition (EMT) through WNT/β-catenin and MAPK signalling

Colorectal cancer (CRC) is one of the most common malignancies and is the second leading cause of cancer death in humans. Tumour suppressor candidate 3 (TUSC3) plays an important role in embryogenesis and metabolism. Deletion of TUSC3 often causes non-syndromic mental retardation. Even though TUSC3 deregulation is frequently observed in epithelial cancers, the function of TUSC3 in CRC has remained unknown. In this study, we observed greater expression of TUSC3 at the mRNA and protein level in clinical colorectal tumour samples compared with paired normal tissues. Gain- and loss-of-function analyses were performed to evaluate the functional significance of TUSC3 in CRC initiation and progression. Immunoblotting, immunofluorescence, and co-immunoprecipitation analyses were used to identify potential pathways with which TUSC3 might be involved. Overexpression of TUSC3 in CRC cells induced epithelial-mesenchymal transition (EMT) in CRC cells, accompanied by down-regulation of the epithelial marker, E-cadherin, and up-regulation of the mesenchymal marker, vimentin. Increased proliferation, migration, and invasion, as well as accelerated xenograft tumour growth, were observed in TUSC3-overexpressing CRC cells, while opposite effects were achieved in TUSC3-silenced cells. In conclusion, our study demonstrated the oncogenic role of TUSC3 in CRC and showed that TUSC3 may be responsible for alternations in the proliferation ability, aggressiveness, and invasive/metastatic potential of CRC through regulating the MAPK, PI3K/Akt, and Wnt/β-catenin signalling pathways.